參數(shù)資料
型號(hào)： M-8880
廠商： Clare, Inc.
英文描述： M-8880 DTMF Transceiver
中文描述： 的M - 8880雙音多頻收發(fā)器
文件頁(yè)數(shù)： 3/13頁(yè)
文件大?。?/td> 841K
代理商： M-8880
causes V
C
(see Figure 5) to rise as the capacitor discharges.
Provided that the signal condition is maintained (ESt remains
high) for the validation period (t
GTP
), V
C
reaches the threshold
(V
TSt
) of the steering logic to register the tone pair, latching its
corresponding4-bitcode(seeTable2)intothereceivedatareg-
ister.
At this point the StGT output is activated and drives V
C
to V
DD
.
StGT continues to drive high as long as ESt remains high.
Finally, after a short delay to allow the output latch to settle, the
delayedsteeringoutputflaggoeshigh,signalingthatareceived
tonepairhasbeenregistered.Itispossibletomonitorthestatus
ofthedelayedsteeringflagbycheckingtheappropriatebitinthe
statusregister.Ifinterruptmodehasbeenselected,theIRQ/CP
pin will pull low when the delayed steering flag is active.
The contents of the output latch are updated on an active de-
layed steering transition. This data is presented to the 4-bit
bidirectional data bus when the receive data register is read.
The steering circuit works in reverse to validate the interdigit
pause between signals. Thus, as well as rejecting signals too
short to be considered valid, the receiver will tolerate signal in-
terruptions (dropout) too short to be considered a valid pause.
This capability, together with the ability to select the steering
time constants externally, allows the designer to tailor perfor-
mance to meet a wide variety of system requirements.
GuardTimeAdjustment:
Thesimplesteeringcircuitshownin
Figure 5 is adequate for most applications. Component values
are chosen according to the formula:
t
REC
= t
DP
+ t
GTP
T
ID
= t
DA
+ t
GTA
The value of t
DP
is a device parameter and t
REC
is the minimum
signal duration to be recognized by the receiver. A value for C1
of 0.1
μ
F is recommended for most applications, leaving R1 to
be selected by the designer. Different steering arrangements
may be used to select independently the guard times for tone
present(t
GTP
)andtoneabsent(t
GTA
).Thismaybenecessaryto
meet system specifications that place both accept and reject
limitsonbothtonedurationandinterdigitpause.Guardtimead-
justment also allows the designer to tailor system parameters
such as talkoff and noise immunity. Increasing t
REC
improves
talkoff performance since it reduces the probability that tones
simulated by speech will maintain signal condition long enough
to be registered. Alternatively, a relatively short t
REC
with a long
t
DO
would be appropriate for extremely noisy environments
where fast acquisition time and immunity to tone dropouts are
required.Designinformationforguardtimeadjustmentisshown
in Figure 6.
Call Progress Filter
A call progress (CP) mode can be selected, allowing the detec-
tionofvarioustonesthatidentifytheprogressofatelephonecall
onthenetwork.ThecallprogresstoneinputandDTMFinputare
common; however, call progress tones can only be detected
whentheCPmodehasbeenselected.DTMFsignalscannotbe
Page 3
M-8880
40-406-00012, Rev. G www.clare.com
F
LOW
697
697
697
770
770
770
852
852
852
941
941
941
697
770
852
941
0 = logic low, 1 = logic high
F
HIGH
1209
1336
1477
1209
1336
1477
1209
1336
1477
1336
1209
1477
1633
1633
1633
1633
Digit
1
2
3
4
5
6
7
8
9
0
D3
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
D2
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
D1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
D0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
*
#
A
B
C
D
Table 2 Tone Encoding/Decoding
Figure 5 Basic Steering Circuit
Figure 6 Guard Time Adjustment
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
M-8880-01P 功能描述:IC TRANSCEIVER DTMF CMOS 20-DIP RoHS:是 類別:集成電路 (IC) >> 接口 - 電信 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS 產(chǎn)品變化通告:Product Discontinuation 06/Feb/2012 標(biāo)準(zhǔn)包裝:750 系列:*
M-8880-01SM 功能描述:IC TRANSCEIVER DTMF CMOS 20-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 電信 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS 產(chǎn)品變化通告:Product Discontinuation 06/Feb/2012 標(biāo)準(zhǔn)包裝:750 系列:*
M-8880-01T 功能描述:IC TRANSCEIVER DTMF CMOS 20-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 電信 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS 產(chǎn)品變化通告:Product Discontinuation 06/Feb/2012 標(biāo)準(zhǔn)包裝:750 系列:*
M-8888 制造商:CLARE 制造商全稱:Clare, Inc. 功能描述:DTMF Transceiver
M-8888-01 制造商:CLARE 制造商全稱:Clare, Inc. 功能描述:DTMF Transceiver
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